Nutrient attenuation in a shallow,gravel-bed river. I. In-situ chamber experiments |
| |
Authors: | John M Quinn Sherry J Schiff |
| |
Institution: | Environmental Geochemistry, University of Waterloo, Waterloo, Canada |
| |
Abstract: | ABSTRACT Dissolved nutrient uptake and metabolism by periphyton in a central North Island gravel-bed river were investigated using recirculating in-situ chambers. Dissolved inorganic nitrogen (DIN) uptake was correlated with photosynthesis and chlorophyll but N uptake and carbon fixation were partly de-coupled indicating storage. Dissolved reactive phosphorus (DRP) uptake was only weakly correlated with photosynthesis. Diatoms and green algae relied on DRP in the water, but Cyanobacteria met part of their P needs from storage. Dissolved organic nutrients were excreted in both light and dark incubations, with approximately 50% of DIN uptake during photosynthesis excreted as DON. To simulate diurnal variations in nutrients, oxygen and pH existing computer models need to de-couple photosynthesis from nutrient uptake, allow for variable stoichiometry and better quantify recycling of organic nutrients. |
| |
Keywords: | Nutrients nitrogen phosphorus periphyton attenuation photosynthesis |
|
|